For one, you can frequently read what different publishers and agents are tired of, or what they're looking for. You can read lousy queries on several editor and agent blogs (try http://queryshark.blogspot.com/ , http://editorialanonymous.blogspot.com/ , http://pubrants.blogspot.com/ , http://rejecter.blogspot.com/ http://www.evileditor.blogspot.com/ )and tweak yours accordingly.
For another, you can read about publishing trends on free feeds like Publisher's Lunch: http://www.publishersmarketplace.com/lunch/subscribe.html and Galley Cat: http://www.mediabistro.com/galleycat/ . Trends are important, although you should always plan on writing what you like.
If you find yourself distracted by the Internet (surfing around instead of writing) then just sign up for the feeds at the bottom of the blog pages. It's easy to do and your computer checks for blog updates on the blogs. There's a "feeds" tab next to your "favorites" tab if you use Windows Internet Explorer. The feeds will be in bold if there are new blogs to read. Limiting myself to just reading updates helps me resist the temptation to surf around.